#include <iostream>
#include <cstdio>
using namespace std;
int step;
double s;
double a;
double now = 2.0;
int main() {
	cin >> s;
	while(a <= s) {
		step++;
		a += now;
		now *= 0.98;
	}

	printf("%d", step);
	return 0;
}
